<template>
    <div class="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
<script>
export default {
    name: 'SIdentify',
    props: {
        identifyCode: { // 默认注册码
            type: String,
            default: '1234'
        },
        fontSizeMin: { // 字体最小值
            type: Number,
            default: 25
        },
        fontSizeMax: { // 字体最大值
            type: Number,
            default: 35
        },
        backgroundColorMin: { // 验证码图片背景色最小值
            type: Number,
            default: 200
        },
        backgroundColorMax: { // 验证码图片背景色最大值
            type: Number,
            default: 220
        },
        dotColorMin: { // 背景干扰点最小值
            type: Number,
            default: 60
        },
        dotColorMax: { // 背景干扰点最大值
            type: Number,
            default: 120
        },
        contentWidth: { // 容器宽度
            type: Number,
            default: 90
        },
        contentHeight: { // 容器高度
            type: Number,
            default: 38
        }
    },
    methods: {
        // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min)
        },

        // 生成一个随机的颜色
        randomColor(min, max) {
            let r = this.randomNum(min, max)
            let g = this.randomNum(min, max)
            let b = this.randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
        },

        drawPic() {
            let canvas = document.getElementById('s-canvas')
            let ctx = canvas.getContext('2d')
            ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = '#e6ecfd'
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i)
            }
            this.drawLine(ctx)
            this.drawDot(ctx)
        },

        drawText(ctx, txt, i) {
            ctx.fillStyle = this.randomColor(50, 160) // 随机生成字体颜色
            ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei' // 随机生成字体大小
            let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
            var deg = this.randomNum(-30, 30)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)
            ctx.rotate(deg * Math.PI / 180)
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
        },

        drawLine(ctx) {
            // 绘制干扰线
            for (let i = 0; i < 4; i++) {
                ctx.strokeStyle = this.randomColor(100, 200)
                ctx.beginPath()
                ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.stroke()
            }
        },

        drawDot(ctx) {
            // 绘制干扰点
            for (let i = 0; i < 30; i++) {
                ctx.fillStyle = this.randomColor(0, 255)
                ctx.beginPath()
                ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
                ctx.fill()
            }
        }
    },
    watch: {
        identifyCode() {
            this.drawPic()
        }
    },
    mounted() {
        this.drawPic()
    }
}
</script>
